Zonal centrifuge attachment



March 3, 1970 Filed ma 15, 1968 NR. HARBOTT ZONAL CENTRIFUGE ATTACHMENT3 Sheets-Sheet 1 March 3, 1970 N. R. HARBOTT ZONAL CENTRIFUGE ATTACHMENT3 Sheets-Sheet 2 Filed May 15 1968 Hllll March 3, 1970 N. R. HARBOTT3,498,532

ZONAL CENTRIFUGE ATTACHMENT Filed May 15 1968 s Sheefis-Sheet 5 xwiUnited States Patent O 3,498,532 ZONAL CENTRIFUGE ATTACHMENT NormanRichard Harbott, Sussex, England, assignor to MSE Holdings Limited,Crawley, Sussex, England, a British company Filed May 13, 1968, Ser. No.728,432 Claims priority, application Great Britain, June 19, 1967,28,277/ 67 Int. Cl. B04b 11/04, /10, 7/12 U.S. Cl. 233-16 5 ClaimsABSTRACT OF THE DISCLOSURE This invention relates to zonalcentrifugation used for tissue fractionation and 'virus isolation andconcerns a zonal centrifuge attachment.

In zonal centrifugation, a density gradient is maintained in a hollowcylindrical zonal rotor spinning about its axis of symmetry. Thegradient and the sample are introduced into the rotor whilst it isspinning by liquid entry and exit lines having a rotating seal with therotor. The rotor conventionally has septa dividing the rotor intosegments to prevent swirling of its contents. The components of thesample migrate through the density gradient in a manner dependent upontheir densities and can thus be separated, either by so-called ratezonal separation or by isopycnic zonal separation.

For very high speed work, at tens of thousands of r.p.m., it isadvantageous to use a rotor which is tall but which has a relativelysmall diameter. In addition to conventional means such as a taperedrecess at the lower end of the rotor for coupling the rotor to thecentrifuge motor, the rotor has a top supporting bearing because of itsheight.

A problem with such a rotor is that, because of its height, it is usedwith a special centrifuge having a guard bowl of greater height than instandard centrifuges to accommodate the rotor within the centrifuge.

It is an object of the present invention to provide a zonal centrifugeattachment suitable for a standard centrifuge.

In accordance with the invention, there is provided a,

zonal centrifuge attachment for a centrifuge having a cover, which is tobe apertured to accommodate the attachment, the attachment comprising:an open-ended housing to be positioned on said cover so as to beupstanding therefrom and to cover the aperture in said cover; a hollowcylindrical zonal centrifuge rotor having such dimensions, with an axiallength greater than its diameter, that said rotor can be supportedpartially within said housing and will extend through said aperture insaid cover when said housing is positioned as aforesaid; coupling meansat one end of said rotor for coupling said rotor to the motor of saidcentrifuge; liquid entry and exit means supported by said housing forintroducing liquid into and removing it from said rotor during rotorrotation; and bearing means for rotatably supporting said rotor at itsother end relatively to said housing.

For a better understanding of the invention and to show how the same maybe carried into effect, reference Patented Mar. 3, 1970 "ice will now bemade, by way of example, to the accompanying drawings, in which:

FIGURE 1 is a diagrammatic view of a standard centrifuge partially cutaway;

FIGURE 2 is a diagrammatic view of the centrifuge of FIGURE 1 carryingan attachment and again shown partially cut away;

FIGURES 3A and 3B together form a cross-section of an attachment showingparts of a centrifuge in phantom.

FIGURE 1 shows a standard M.S.E. centrifuge operable at 65,000 rpm. Thecentrifuge comprises a casing 1 having a cover plate 2 adapted to beslid into the illustrated position upon an Oring to give a vacuum-tightseal. The compartment within the casing is to be evacuated by a duct(not shown). The casing contains a centrifuge rotor 3 of titaniumcoupled to be driven by a motor 4 having a shaft portion 5 of taperedform for engaging in a recess in the underside of the rotor 3. As anindication of the overall dimensions, it is pointed out that the rotor 3of this embodiment has an axial length of about 5 inches and a diameterof about 7% inches. The casing 1 also contains a bowl 6 secured to themotor 4 and surrounded by piping 7 forming a coil of refrigerationequipment which is not shown. The bowl has an axial length of about 9 /2inches and a diameter of about 15 inches.

FIGURE 2 shows the centrifuge of FIGURE 1 adapted for operation forzonal centrifugation. It has been found desirable to employ for suchcentrifuging a special form of rotor having an axial length in excess ofits diameter, the diameter being smaller than that of a conventionalrotor such as is shown at 3 in FIGURE 1. To accommodate the zonal rotor8, having sector shaped compartments, the cover plate 2 is provided withan aperture 9 closed by an upstanding open-ended housing 10 covering theaperture 9. The rotor 8 is supported at its upper end by a steadyingbearing 17 and extends into the housing 10 which carries an arrangement11 for continuous feed of liquid to and from the rotor -8 during rotorrotation. In this case, the rotor 8 has a diameter of about 5 inches andan axial length of about 13 inches. The rotor is recessed on itsunderside to receive the existing shaft portion 5 of the motor 4. Thearrangement 11 also has provision for feeding a cooling medium to thetop bearing 17 and rotating seal of the attachment.

FIGURE 3 shows the attachment in cross-section. The housing comprises aguard ring 12 recessed into the aperture 9 in the cover plate 2, anO-ring 13 being provided to effect a vacuum-tight seal between the coverplate 2 and the ring 12. An annular plate 14 is bolted to the upper endof the ring 12, this plate 14 being closed by a further annular plate 15bolted to the plate 14 and carrying the liquid supply and exitarrangement 11. The rotor 8 is also shown in this figure.

In practice, a special apertured cover plate 2 may be provided for theattachment, or the existing cover plate of a standard centrifuge may beadapted by forming the aperture 9 in it and by providing this aperturewith an O-ring sealed cover plate (not shown) for operation in the modeillustrated in FIGURE 1. For zonal centrifugation, the guard ring isplaced in position on the cover plate 2 and cover plate 2 is slid intoits final position. The

rotor is then inserted into the centrifuge to engage the lower end ofthe rotor with the shaft portion 5 and the plate 14 and its attachmentare placed on the ring 12. Bolts 16 are then inserted and tightened tocomplete the assembly. When a vacuum is produced within the centrifnge,the guard ring 12 is thereby sealed to the cover plate 2.

The described attachment is used conventionally, that is to say thedensity gradient and the sample are introduced while the rotor isrunning at low speed, whereafter the rotor is run at high speed untilrate ZOnal or isopycnic zonal separation has occured. Then the rotor isslowed down and the entire rotor contents are removed while the rotor isrunning. It will be apparent that with a modified rotor core theattachment can be used for contiuuous-fiow zonal separation in Which thesample is fed continuously into the rotor running at high speed and thesolution in which the sample is suspended is removed continuously. Thissolution has a density less than that of the lightest part of thegradient.

I claim:

1. A zonal centrifuge attachment for a centrifuge having a cover, whichis to be apertured to accommodate the attachment, the attachmentcomprising: an open-ended housing to be positioned on said cover so asto be upstanding therefrom and to cover the aperture in said cover;

a hollow cylindrical zonal centrifuge rotor having such dimensions, withan axial length greater than its diameter, that said rotor can besupported partially Within said housing and will extend through saidaperture in said cover when said housing is positioned as aforesaid;coupling means at one end of said rotor for coupling said rotor to themotor of said centrifuge;

liquid entry and exit means supported by said housing for introducingliquid into and removing it from said rotor during rotor rotation; and

bearing means for rotatably supporting said rotor at its other endrelatively to said housing.

2. An attachment as claimed in claim 1, wherein said housing comprisesan annular wall at one end of which is an annular plate through whichsaid liquid entry and exit means extend in vacuum-tight fashion and uponwhich said bearing means is mounted.

3. An attachment as claimed in claim 2, wherein said plate is readilydetachable from said annular wall.

4. An attachment as claimed in claim 1, wherein said rotor and saidentry and exit means are designed for continuous-flow zonalcentrifugation.

5. In a centrifuge having a guard 'bowl closable in vacuum-tight fashionby a cover to define a rotor receiving space and a motor for driving arotor within said space, the improvement which comprises:

said cover having an aperture permitting access to said space; andopen-ended housing mounted on said cover in vacuum-tight fashion andcovering said aperture; a hollow cylindrical zonal centrifuge rotorhaving a length greater than its diameter and extending from said spacethrough said aperture into said housing;

coupling means coupling the end of said rotor within said space to saidmotor;

bearing means supporting the end of said rotor within said housing withrespect to said housing; and liquid entry and exit means for introducingliquid into and removing liquid from said rotor during rotor rotation.

References Cited UNITED STATES PATENTS 2,878,992 3/1959 Pickels 233--26X 3,050,239 8/1962 Williams 233-26 X 3,304,990 2/1967 Ontko 233--263,317,127 5/1967 Cole 233-26 ROBERT W. JENKINS, Primary Examiner US. Cl.X.R.

